Analysis fields at header level on sales ledger transactions (for aged debtors breakdown and commission calculations etc)

We now have several customers who need to be able to break down their outstanding debtor balances according to particular criteria (e.g. the brand of goods sold, or the event being invoiced) and/or perform calculations (e.g. commission) based on invoices paid. In SOP/POP you have the option of header and line level analysis codes. However, these do not pass through to the ledgers. What would be useful would be to have analysis field drop-down options which could be used at header level (unlike transaction analysis codes/nominal codes/cost centres at line level) on sales invoices and receipts. On the sales invoices originating from SOP these should take the header level analysis code value from the sales order. This would then allow aged debtor reports to divide the transactions on a given customer account into these relevant streams and to determine the value of invoices paid in a particular period relating to a particular brand/event for commission calculations.